Phase shifter



L. A. DE ROSA PHASE SHIFTER June 6, 1950 5 Sheets-Sheet l Filed Oct. 20. 1945 aan A TTOR/VE Y L. A. DE ROSA `lune 6, 1950 PHASE SHIFTER 5 Sheets-Sheet 2 Filed Oct. 20. 1945 INVENTOR. OU/5 4. @f5/P054 TTOPNEY L. A. DE ROSA PHASE SHIFTER June 6, 1950 5 Sheets-Sheet 3 Filed OGl.. 20, 1945 .am wm Il .QN s s s m@ &N\ 7% %N nh m. QN. @QN NM. BW WN QN w .Sv NW mM .mv e Qmmv o Nn 0% QQ NW Ww u 7 .0 OAR TM N E. V A m U W/ L. A. DE ROSA June 6, 1950 PHASE SHIF'TER 5 Sheets-Sheet 4 Filed Oct. 20, 1945 INVENTOR. OU/5 A. olf/P0514 BY L. A. DE ROSA June 6, 1950 PHASE SHIFTER 5 Sheets-Sheerl 5 Filed Oct. 20, 1945 Patented `une 6, 195:0

Louis vA.deRosaVBloomfeld, N. J.,- assigner to Federal Telephone and Radio Corporation, New York, NJY., a corporation of Delaware Application-:October 20, 1945,l Serial Nof623,468

4 Claims.

This :invention relates --to l alternating current @phase Shifters,y and more particularly to aphase `shifting device for shitting fphase linearly -'-throughoutva;scalefrange/rom 0 to 350i.

"- One of" thel objects of my inventionis to pro- A Ivideea compact, highiyaccurate,phase shifter @capable-W of Vfine adjustments for shifting. phase linearlythroughsubstantially 360.

Another-objectofmy invention is to provide fa* linear phasefshifter toy which alternating cur- Irent isapplied-and -an outputpulse is produced deiining avgivenpoint on the period oi `the alternating current'which-may be used as a reference 4pulse forusedn .radio detection systems and for zother purposes.

'A furtherobject-ofthe invention is to provide -alinear-phase shifter-with means whereby the rzero .calibrationi thereof can be' quickly checked without changing the phase adjustment thereof.

`A- still-further object of my invention is to provide a linear-phase shifter in which phase shifting is accomplished linearly during the manual linear adjustment of' a control means or drive means for said phase shifting'device.

--fl`heaboveI and other objects of the invention Will-become more apparent upon consideration JVof--the following detaileddescription to-be read in l:connection with-the accompanying drawings, in

which Fig.- 14 a schematic wiring and blockdiagram -of `one embodiment of the invention;

4-1ig.2` is -a graphical illustration of the'phase shifting operationA according -to my' invention;

VFig 3 is a. graphical'illustration `of va vector diagram showing the variation Ain amplitude of the' output voltage vof the phase shifter foi-dif- --ferent degrees of phase shift;

'Fig. v4 isa fragmentary. plan view of thephase tshifter `.showing 'certain construction features -1thereof;

VfFigs-lct isa view in vertical section of a portion Fig. 5 is a vertical sectional view of Fig. 4 with parts-broken away to -showMdiagrammatically the :arrangement `ofthe impedance network-of the .f 4phase shifter;

YFigsi'fand 'Tareschematic illustrations of further embodiments of the-invention; and

T'Fig.f8 is a-fgraphical illustration showing the relationship between a'desired phase shift accom- -plished'fthrough .the 'use of.Y my invention asreff-Inphase 'comparison direction finding systems lIandf-radio.detectiont systems there is great --neces- `sity for obtainingY a linear phase shift having no deviation from. llinearity atany point throughout substantially 360. This is particularly so where the: phase shift indication is desired at somere- Vmotefpoint, Vsuch as may beprovided by using a Selsynmotor system.

f Impedance networks have been -designed to cooperate with other components-such as capacitive reactances and inductive reactances to compensate for non-linearity, but such systems 'are unable to overcome certainfobstacles indesign and operation .My inventionY inone form, resides in a camadjustment-controlled differential to providea compensating .motion to effectively produce a1 fiinearphase sliiita when adj ustments in, phase areinadebyahand wheelonother drive means.

fExper-inientsiiave shown' that certain errors Yoccurintphase shiitadjacentopposite ends 0l' eachfpart of theimpedance network. According to the.. present Virnfention the differential. drive is i arranged to 'produce lan advancement or. retarda- -tion': or the-:position Yora movable contact-along f the'lv impedance network,` this variation -to occur `i'epetiticusly throughout-.eachsection:of thenetwork.

-viurning'-rst :tof-Fig. l--oi the drawingsfthe 'f embodimentor" the` invention therein illustrated includes aipo1',e1cit1ometerl `resistor i which is-macle orresistorwire closely `wotmd in aesmall diameter and"ai1'an'ged preferably in the-form oifa spiral `v`about "an -insulatordrum 2 #with the two-ends thereof' connectedtcgetnerl'toly form'in erect a y continuousresistorelement such'as illustrated in Fig. l. The potentiometer resistor isdividedinto '1f sixse'cti'onsf as indicated by-:the points oft-network connections 3 -to s. Connection: points'3,r4 and tfhave applied-thereto, through parts' or` thefnetiworl:`iiereinarterdescribed; one side tiefen' alter- 401 'hating current source lo.

Y*opposite side iiv of :the -samealternating current l Thepointsof connectioni-j and l are 4`connected-by?- thenet'work to source. The source l` includes a transformer l2,

v"thesecordary ofwhich is connected across resistors i3 andV il to 'the' two sides" 9 and l i The 'center cap l5 f'thesecondary is connected-to a center connection `vit Abetween there'sistors i3 "andi i4, and'grounded. In' order to insure accurate divisionV of the 4secondary 'with respect to ground,` the' sideconnection",l is providedwith a movable contact Vi` so4 that proper adjustment or" this balance' canbe obtained.

If desired,` the load resistors I3 and I4 may be f balanced by replacing A,the transformer `I2 by" two identical transformers, one placed across the resistor I3 and the other placed across the resistor I4.

The impedance network associated with the potentiometer coil I comprises in this embodiment a number of resistors and condensers. The connection points 3 and 6 are provided with two resistor elements R3, Ras and Re, Rta respectively. These resistors are selected equal in value. The resistors R3 and Re and connected to the opposite side connections 9 and II respectively and the resistors Rza and Rea are connected to ground at a common ground connection I 8. Since the IR drops across these resistors are in phase with the applied voltages between the two sides 9 and II on the one hand and ground I8 on the other hand, the phase at the points 3 and 6 will be exactly 180 difference in accordance with the phase difference between the opposite terminals of the secondary of the transformer I2. In Fig. 2 applied voltage across the side connections 9 and II for an instantaneous value is represented by the curves E3 and Ec.l Since the IR drops to the points 3 and 6 are in phase with the voltages between the side connections 9 and ground, and II and ground, the curves E3 and E6 represent the voltages at the points 3 and 6. Using point 3 as a reference point for the point IS will then represent a phase difference therefrom of 180.

To point 4 (Fig. 1) is connected a condenser C4 and a resistor R4. to the side 9 thereby providing a phase advancement at point 4 with respect to the phase at point 3. The resistor R4 is connected to ground I8, and the ratio of the IR drop of the resistor R4 with respect to the reactance of condenser C4 determines the shift in place from point 3 to point 4. These values of Ri and C4 are so selected as to provide a ratio giving point 4 a phase advancement of 60 with respect to point 3. This phase shift is indicated by the curve E4 (Fig. 2)

Point 5 is likewise provided with a resistor R5 and a condenser C5. The connecting relation of these two elements with respect to the side I I and ground I8 is the reverse of the connections R4 and C4. That is, the resistor R5 is connected to Vthe opposite side connection I I and the condenser C5 is connected to ground I8. In this reverse arrangement a condenser resistor ratio provides a phase radiation with respect to the side II to ground. Thus, since point 6 is 180 different in phase from point 3, a phase radiation of 60 will make point 5 120 out of phase with respect to point 3. This phase condition of point 5 is indicated by curve E5 (Fig. 2) g Point I is provided with a resistor R7 connected to ground I8 and a condenser Cv connected to the side I I. This provides a phase advancement sim- Yilar to the R.C. ratio for point 4. This phase advancement is with respect to point 6 and gives point 'I in a clockwise direction in Fig. 1 a phase difference with respect to point 3 of 240 as indicated by curve E7 (Fig. 2). Y

Point 8 is provided with a condenser Cs connected to ground I8 and a resistor Ra connected to the side 9. This provides a phase retardation of 60 with respect to the voltage applied to point 3 as indicated by curve Es. The point 8 also has a corresponding phase advancement with respect to point 'I so that the phase difference in a clocklwise direction with respect to point 3 is 300.

It will be understood that R4, R5, R1 and Rs are of a given resistance and condensers C4, C5. Cv and Ca are of a given capacitance so that advancement and retardation of phase, as the case may be, between the successive points will be 60 The condenser C4 is connected through a cable 22.

for each section. It will also be understood that instead of measuring or Calibrating the phase shifter in a clockwise direction, the calibration may be counter-clockwise.

The output voltage from the phase shifter is taken oiI by a movable contact I9 which engages the potentiometer resistor I and is adapted to be moved therealong from point to point as desired. As the contact I9 is moved from point 3 toward point 4, the phase difference of the output voltage is an advancement with respect to the phase at point 3. This variation of the total phase shift between points 3 and 4 is proportional to the position at which the contact I9 is located between these two points. Since the contact may be 'moved the full length of the potentiometer resistor, the output voltage may be given any desired phase shift up to 360 with respect to the phase of the applied voltage at point 3. It must be understood however, that the variation of the phase between points 3 and 4 along the resistor may not be Alinear due to errors introduced by irregularities'in the operating characteristics of the inductive reactances, capacitive reactances and resistance values shown at C4, R4 and Rca. Before proceeding to a further discussion of means of overcoming this non-linearity, we shall discuss certain construction features to secure a better understanding of my invention.

Referring now to Figs. 4 and 5, thepotentiometer resistor I is provided with the connection points' 3 8 through openings in the insulator drum 2 so that the connections to the resistors and condensers are passed inwardly of the drum.

The resistors and condensers may be located in the drum or preferably on the supportZI) where they are easily accessible for adjustment during testing of the assembly. The wires 2l connecting the resistors and condensers are led The connection arrangement makes for a compact phase shifter whereby the movable contact I9 is movable about the outside of the drum.

For adjustment of the contact I9, the contact is supported on an arm 23 carried by an internally threaded hub 24 supported on a threaded shaft 25. The hub 24 also carries a gear 26 which meshes with an elongated pinion 2l.A The pinion 21 is carried by a shaft 28 suitably supported in a parallel relation with respect to the shaft 25. Shaft 23 is connected to one of two bevel gears 29a of a conventional differential gear assembly. A ring gear 30 is held in a steady position by an actuating rod 3l articulated'with a lever 32. Planetary gears 33 held in ringl gear 30 mesh with the alternate bevel gear 29D.- A hand crank 34 carried by a shaft 35 mounted on brackets 36, 3l is arranged to drive a shaft 3B through bevel gears 39 and 40. Mounted further along on shaft 33 is a bevel gear 4I meshing with bevel gear 42 to drive shaft 43 which in turn drives bevel gear 29h of the differential gear assembly.

' When the crank 34 `is operated, rotation.' of shaft 43 in one direction causes shaft 28 to-ro tate in the opposite direction atthe same speed, but only so long as ring gear 30 is held steady. Mounted on shaft 38 between bevel gears 4D and 4I is a worm gear 44 meshing with worm drive gear 45, upon which is mounted a lift cam 46 bearing against lever 32 for a portion of the revolution of gear 45. Lever 32 is supported midway by bearing points 41. As lift cam 46 bears against one end of lever 32 a corresponding pressure at theother end of 1ever32 is exerted against actuating rod 3 I, causing` -anv upsetof the" stead'i'fl state' of rin'g'gear`30. Thisfupset is',gradual,"aclcorai'ngto the shape f iiftfcamlefand the rotation of ring gear '3U occurs A onlyy during the` periodof contact b'etweenflift' cam'46 Yandlever" 32,iingV gear 3U taking up its`origirial`po'sitionf as 'soonas lever '32 bears' against V`'I;h=`;-fbase`of gearV 45 during portions of the revolutionof the gear '45.

Bevel gears 39 and`40 shouldprefe'rablyihave a ratio of l to 1, as should'vbevel 'gearsl`4l` 'andl 42.m The ratio of wormV gearl 44 to'worm'drive gear'f45 should preferably bef6 to 1. AIt will therefore be clear that during tlierot'at'ion ofY shaft 38 a similar rotation equal in speed but opposite in direction "willfoccur atshaft Q28.' However, this voccurs 'throughout' 'a greater or lesser 'number ofl revolutions equal tojthe" size orshape Vof lift `cam 45 on gear '45. Dueto the fact that theratio "of 6 to 1 Vof the 'worm gear vassemblyprovides an advancement" or rei tardation in angularv position of shaft 28at some time during a cycleof six revolutions'- of shaft 38, it Will be YClefa'tl'ia-t vlinear motion of shaft 38 will `provide a non-linearmotion of Shaft 23.

Measuring in circular mechanical Hc'legre's'of rotation, shaft 38in a cycle'of six revolutions will pass through 2160 degrees angular 'd'is'pl'ace-t me1 i t and correspondinglyshaft 2I3fwillwpassV through the same number o f"degfree's` Dependent upon theA position` in thencycle andthe size of lift cam 46, a retardation or advancement angular displacement of shaft 28 will occur. Shaft 28 transmits through pinion4v21 this cyclical rotation which inturn is transmitted to gear 26. The ratiooffpinion 21 and gear 26 should preferably be 6 to l also. 1 p Y We now have clearly shown that by turning hand wheel 34 six times, movable contact I3 revolves through 360 of rotation while bearing againstresistor I. At a predetermined number of degrees in the circular rotation` of movable` contact I9 its position has been-advanced-or retarded non-linearly with respect tojthe linear motion of hand wheel 34'according to the positioning of lift cam 46 in'its cycle of rotation, as well'ias its size.v Additionally, hub 24 is caused to rotate and at the same vtime traverse the shaft 25 in an axial directionfThis causes the contact I9. to follow the spiral f rthe potentiometer-resistor I as wound on drum 2. f

For indication of the phase Ashift ofVv the output voltagef provide'fa rotatably' mounted, cal;`

ibrat'e'ddrum 41 contained in` housing g .The 5 housing has" a window'glthough Wh 'hthe calibrations onthe'drum'arejfviewed. TheI ruin 41 is driven by asuitable vreductinn gear"shwn generally at 50 connected t0 shaft 38. Preferably, the drum 41 is arranged to make one complete rotation for a complete movement of contact I9 from end to end along the length of the potentiometer element I.

The amplitude of the output voltage is indicated by a vector I9a in Fig. 3. As the contact I9 is moved along the potentiometer resistor I, the vector I9a will be moved almost proportionally in angular displacement, and will trace an amplitude output curve ISb. This output voltage varies in amplitude from point to point because of the resistance of the potentiometer element I. As the contact approaches each point, the voltage will increase to a maximum and when the contact approaches the center portion of la sectionofj Ythe poteritiometer elementV lthe amplitudewill'zapprach a minimum.'4

the Contact is conducted through relay `-contacts 5I`, `52 to anjampler 53 of Yonej'or morestages to producejthes' pulses is disclosed in detail ,in

issued l sept. 6, 1949,

' To 'check the'zero vphase calibration of the phaseshi'fter without having to `crank the con-y f tact lI9 back "to point'BQI provide' a relay contact" By controlling energiZa- 56 conn-ected'to point 3. tion" of V,relay coil 51 by switch 58, theA movable contact 52 can'be made to 'give-V alternately'zero phase and the phase shift according to thelocaltion ofthe contact I9.

For remote indications 'of V`phase shift, the coni* tact adjustment'may be transmitted over a Sel-i syn motor circuit. For this purpose, I show a local ,Selsyn motor 59 driven'off the shaft`38 by a worm' 60 and wormgear 6I. u

In Figs. 6 and 7,1 have shown two additional embodiments of the invention. In Fig. 6, the impedance network I comprises resistors which maybe"arranged in'a parallel'series circuit tok provide a Variation in resistance value from point" topointpthroughout 4360 of rotation of Acontact I9. This method(of'fconstruction'jwill result in thep 'rcaductionV of a' substantiallylinear phase shift effectively equivalent toal linear' motion in mechanical deg'ree'spf contact I9,

In Fig. 7 the network comprises 'the combina-V` tion'ofresistorsand"condensers as shown in arjran'gement 'of Fig. 1 Vbywresstors "62,"63 and 64,4f

talgigthelplace"ofthe resistive element 'I vof, Figf 1. `These'resistors'arespeciallyformedi or treated after manufacture -to providea tapered" resistance between points 3 `and, 4, points 4 and S'andpOints 5 and 6. One preferable method' of, obtaining this tapered resistance is by'causirig' resistiveelementfl to be'reduced'tin diameter'Y or crossV section by an abradingoperation "afterit hasi been wound` on drum* 2. This "abradingi operationis performeclffor"each'A 60 portion of resistive `element I, andfacc OrdingV to the par--V ticular values chosen for the condensers and Vre-' sistors of the network, the portions of each 60"" section may be so abr'aded as to`provide a variation in resistance at a point or series'r of points therealong. This variation in resistive value is made to compensate for any advancement or retardation of phase shift as contact I9 is moved along resistor I. However, the method of assuring linear phase shift shown by Fig. 4 is prefer- 35 able because the effect of changes in temperawhich will be linear, provided the modications therein. Two such circuits are more fullydescribed in my aforesaid copending application, Serial No. 484,795.

In Fig. 8 I show a graphical representation of phase shift which has been exaggerated merely byway of example. The diagram shows a curve A representing a possible phase shift from to 60 as might be obtained in a known resistor potentiometer phase shifter. The curve shows that when the mechanical contact I9 is at a po sition on resistor l corresponding to 15 mechanical, there is an apparent lag in phase shift or deviation from a linear phase shift curve B of 3.5 degrees electrical. In other words, the pointer I9 would have passed through 15 degrees of rotation to secure a phase shift of 11.5 degrees electrical, while at a position of 45 mechanical for pointer I9 the phase shift would become 49.5, or an advancement of 45. In effect the motion imparted by certain embodiments of my invention serves to effectively increase or decrease the number of degrees of mechanical rotation of contact i9 to secure the phase shift as shown by curve B. It will be understood, of course, that curve A is illustrative only and that for different phase shifting networks the variations may be somewhat different, due to materials, workmanship, etc.

While I have disclosed the principles of my invention in connection with several differentA embodiments, it will be understood that these embodiments are given by way of example only and not as limiting the scope of the invention as set forth in the objects and the appended claims.

I claim:

1. The device for shifting phase according to claim 2 wherein the means for compensating for variation in phase shift includes a differential system having a control connection to control translation of movement from the input and output connections thereof, the output connection being in control of the position of said output contact, and means to vary said control connection during movement of said contact between at least certain of said points.

2. A device for shifting phase linearly comprising a drum, an impedance network mounted on said drum including a potentiometer-resistor having parts of the network connected thereto at a plurality of points along the resistor, means for applying one side of an alternating current source to the network parts connected to one group of said points, and the other side of said source to the network parts connected to another group of said points, whereby a phase difference exists between adjacent points, an output contact adjustable along said resistor, the output energy being non-linearly shifted in phase with respect to said alternatingcurrent source upon a given adjustment of said contact between at least two of said points, control means adjustable in mechanical degrees for controlling the adjustment of said contact, and means to vary translation of movement between said control means and said contact to compensate for variation in phase shift of electrical degrees with respect to a corresponding adjustment of said control means in mechanical degrees.

3. A device for shifting phase linearly comprising a drum, an impedance network mounted on said drum including a potentiometer-resistor having parts of the network connected thereto at a plurality of points along the resistor, means for applying one side of an alternating current source to the network parts connected to one group of said points, and the other side of said source to the network parts connected to another group of said points, whereby a phase difference exists between adjacent points, an output contact adjustable along said resistor, the output energy being non-linearly shifted in phase with respect to said alternating current source upon a given adjustment of said contact between at least two of said points, control means for controlling the adjustment of said contact, and means to vary the translation of movement between said control means and said contact to compensate for variation in phase shift with respect to operation of said control means.

4. A phase shifting device for shifting phase linearly comprising a drum, an impedance network mounted on said drum including a potentiometer-resistor having parts of the network connected thereto at points spaced therealong to produce a given shift in phase between such points, the network being arranged to produce a phase shift which is accumulative from point to point, means to apply alternating current to said network, an output Contact adjustable along said resistor, control means to operate said output contact, and means for varying translation of motion between said control means andY said contact in a given manner to insure a phase shift Which bears a linear relation to adjustment of said contact along said resistor.

LOUIS A. DE ROSA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 446,490 Weston Feb. 1'?, 1891 2,085,940 Armstrong July 1, 1937 2,241,6154 Plebanski May 13, 1941 

